1. Field of the Invention
The invention relates to a heat, flame and electric arc resistant fabric for use as single or outer layer of protective garments.
2. Description of Related Art
A garment protecting against heat, flame and electric arc is usually very heavy because the mass and the thickness of the garment itself are normally the main factors conferring protection. The wearer of such a garment, like for example the firefighter, is therefore limited in his movements and undergoes heat stress so that the overall wear comfort strongly decreases. In the last twenty years, attempts have continuously been made to develop new materials in order to improve the wear comfort of such protective garments. For example, lighter but more voluminous insulating materials have been developed for this purpose. These materials confer more lightness to the final protective garment but they might affect the respiratory activities of the wearer due to their cumbersome dimensions. Furthermore, the freedom of movement is not necessarily improved by using these materials.
Garments protecting against heat, flame and electric arc are usually made of one or more layers. The choice of the different materials and of the number of layers constituting the final protective garment depends on the specific application of the garment itself.
When designing a new protective garment, care must be taken that all criteria of the relevant national and international norms are fulfilled. As an example, heat and flame resistant garments must be manufactured in accordance with EN-340, EN-531, EN 469 as well as NFPA 1971:2000, NFPA 2112:2001, and NFPA 70E:2000. For instance, a lighter protective garment could be manufactured by simply using lighter materials. However, this is usually associated with a decrease of the mechanical and thermal properties of the protective garment.
U.S. Pat. No. 5,701,606 discloses a firefighter garment having an outer shell and an inner liner functioning as a combined thermal barrier and moisture barrier made of a fire-retardant, closed-cell foam material. The closed-cell foam liner is moisture resistant and provides thermal insulation. The garment disclosed in this prior art document provides good flame resistance but its weight is elevated since it consists of several fabric layers each having a considerable thickness.
U.S. Pat. No. 4,897,886 discloses a firefighters garment having an outer layer, an intermediate layer and an inner layer. Spacer elements are positioned between two of the layers of the garment thus establishing and maintaining an in-between air gap. The invention disclosed in this prior art document aims to improve the heat resistance of a garment but it is not concerned with its weight and all the problems related thereto which have been mentioned above.
U.S. Pat. No. 4,814,222 discloses aramid fibers which are treated with a swelling agent to improve flame resistance. Such aramid fibers are used for the manufacture of garments which, due to the elevated specific weight of the fibers themselves, are heavy and rigid and, therefore, do not provide an adequate wear comfort.
WO 03/039280, which could be a prior right in Europe according to Articles 54(3) and 54(4) EPC, discloses a multilayer material which can be used as inner liner (thermal barrier) in protective clothing, particularly for fire fighters. WO 03/0392280 is totally silent about the use of such multilayer materials as outer layer or single layer of protective clothing.
The problem at the root of the present invention is therefore to provide a heat, flame and electric arc resistant fabric which, if used as single or outer layer of protective garments, enables to increase wear comfort and to improve the dissipation of vapor and heat produced by the wearer.